sega_32x_service_bulletins

SEGAService BulletinQuality Assurance DivisionModelNoDateMega Drive 1 VA4-PAL00812/13/94SUBJECT:While using the MD1VA4 with the 32X problems like the screen shaking.game sound slowsdown and/or the game locks up.REASON:While'using the MDIVA4 with the 32X at room temperature,it has been found that whencertain IC's,capacitors,etc.heat up they cause the screen to shake.slow the game soundand cause the came to freeze.MODIFICATION:The signal shape of the EDCLK must be improved to fix this problem,see CIRCUITCHANGE below.DETAILS:1.Change C92 from a 61pf capacitor to a 33pf ceramic capacitor.It is important thatthe capacitor be located next to IC4.2.Remove FB7 and insert a jumper wire or short out FB73.Remove C112.This is a 33pf ceramic capacitor that has been addedto the back side of the circuit board.It is connected to the top side of C19.4.Add a jumper wire to the back side of the circut board between the top of Ci0(thisshould be the same point electronically as IC4 pin 31)to ground (the middle pin ofEM16 is recommended).Please be sure to use a slightly heavier gage of wire toground (heavier than AWG28 with a wire diameter of 0.38mm).Circuit ChangeEDCLKFB7MARS(Short out)下宁VDPC92/51p33pC112/33pC92/33pSchematics/Diagrams Attached☒